Marital status, education, and income in relation to the risk of esophageal and gastric cancer by histological type and site

Abstract

BACKGROUND Marital status, income, and education might influence the risk of esophageal and gastric cancer, but the literature is limited. A large study addressing subtypes of these tumors was used to clarify these associations. METHODS A nationwide, Swedish population-based cohort study from 1991 to 2010 included individuals who were 50 years old or older. Data on exposures, covariates, and outcomes were obtained from well-maintained registers. Four esophagogastric tumor subtypes were analyzed in combination and separately: esophageal adenocarcinoma, esophageal squamous cell carcinoma, cardia adenocarcinoma, and noncardia gastric adenocarcinoma. Poisson regression was used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs). Analyses were stratified by sex and adjusted for confounders. RESULTS Among 4,734,227 participants (60,634,007 person-years), 24,095 developed esophageal or gastric cancer. In comparison with individuals in a long marriage, increased IRRs were found among participants who were in a shorter marriage or were never married, remarried, divorced, or widowed. These associations were indicated for each tumor subtype but were generally stronger for esophageal squamous cell carcinoma. Higher education and income were associated with decreased IRRs in a seemingly dose-response manner and similarly for each subtype. In comparison with the completion of only primary school, higher tertiary education rendered an IRR of 0.64 (95% CI, 0.60-0.69) for men and an IRR of 0.68 (95% CI, 0.61-0.75) for women. Comparing participants in the highest and lowest income brackets (highest 20% vs lowest 20%) revealed an IRR of 0.74 (95% CI, 0.70-0.79) for men and an IRR of 0.83 (95% CI, 0.76-0.91) for women. CONCLUSIONS Divorce, widowhood, living alone, low educational attainment, and low income increase the risk of each subtype of esophageal and gastric cancer. These associations require attention when high-risk individuals are being identified.